Transmissive single-mode fiber optics star network

Abstract

Apparatus and method for interconnection for fabrication of combinatorial transmissive star couplers suitable for single-mode fiber optic local area networks. Various types of couplers including evanescent wave couplers are utilized to synthesize artibrarily large fiber optics star couplers free of multi-path interference providing high quality single-mode capability.

What is claimed is. 
     
       1. A method of constructing a single-mode fiber optics 2N-star coupler free from multi-path interference utilizing 2-star fiber optics couplers having two inputs and two outputs where N=2 n  and n is an integer, said method beginning with n=1 comprising the steps of: (a) coupling an output of a first N-star coupler and a corresponding output of a second N-star coupler to the input of a unique 2-star coupler for each output of said first and second N-star coupler to obtain an N-star coupler where 2N=2 n+1  ;   (b) repeating step (a) at least once utilizing 2N-stars constructed according to the previous repetition as the N-stars until the desired star size is reached.   
     
     
       2. The method of claim 1 wherein each 2-star coupler is a 50% beam splitter. 
     
     
       3. The method of claim 1 wherein each 2-star coupler is a fused fiber coupler and the step of coupling comprises forming fused couplers from a plurality of continuous optic fibers such that the fused couplers are coupled by continuous optic fibers. 
     
     
       4. The method of claim 1 wherein each 2-star coupler is a polished fiber coupler and the step of coupling comprises forming polished fiber couplers from a plurality of continuous optic fibers such that the polished fiber couplers are coupled by continuous optic fibers. 
     
     
       5. A combinatorial single-mode fiber optics M n  -star coupler free from multi-path interference, where M and n are integers and where M is greater than two, comprising: a plurality of single-mode M-star fiber optics couplers;   coupling means for intercoupling the single-mode M-star fiber optics couplers such that there are M n  inputs and M n  outputs with only one path from any said input to any said output and such that the single-mode fiber optics M-stars are aggregated in layers from input to output to form progressively larger stars until a single-mode fiber optics M n  star coupler is formed, thereby providing a hierarchic structure.   
     
     
       6. The combinatorial single-mode fiber optics M n  -star of claim 5 wherein the M-stars and coupling means are integrated on a monolithic integrated optics substrate. 
     
     
       7. A single-mode, wide bandwidth fiber optics local area network free from multi-path interference comprising: a plurality of terminals, each having a fiber optics input and a fiber optics output, for receiving and transmitting signals;   a combinatorial, single-mode hierarchic fiber optics N-star coupler comprising intercoupled single-mode 2-star couplers for coupling an average of the plurality of terminal outputs of each of the terminal inputs.   
     
     
       8. The combinatorial single-mode fiber optics M n  -star coupler of claim 5 wherein the M-star couplers comprise beam splitter means for splitting incident light into two beams, lens means for focusing incident light and a plurality of optical fibers for coupling M inputs to the lens means and beam splitter means and for coupling M outputs from the lens means and beam splitter means, and wherein the optical fibers, lens means and beam splitter means are configured such that such output is the average of all inputs. 
     
     
       9. The combinatorial single-mode fiber optics M n  -star coupler of claim 5 wherein the single-mode fiber optic M n  -star coupler is planar. 
     
     
       10. The combinatorial single-mode fiber optic M-star coupler of claim 5 wherein the single-mode fiber optics M-stars are aggregated to form a structure which is both hierarchic and reverse hierarchic and which is planar.